Analyte detection in physiological fluids, e.g. blood or blood derived products, is of ever increasing importance to today's society. Analyte detection assays find use in a variety of applications, including clinical laboratory testing, home testing, etc., where the results of such testing play a prominent role in diagnosis and management of a variety of disease conditions. Analytes of interest include glucose for diabetes management, cholesterol, and the like. In response to this growing importance of analyte detection, a variety of analyte detection protocols and devices for both clinical and home use have been developed.
One type of method that is employed for analyte detection is an electrochemical method. In such methods, an aqueous liquid sample is placed into a sample-receiving chamber in an electrochemical cell that includes at least two electrodes, e.g., a counter electrode and a working electrode. The analyte is allowed to react with a redox reagent to form an oxidizable (or reducible) substance in an amount corresponding to the analyte concentration. The quantity of the oxidizable (or reducible) substance present is then estimated electrochemically and related to the amount of analyte present in the initial sample.
Such systems are susceptible to various modes of inefficiency and/or error. For example, where the physiological sample being assayed is whole blood or a derivative thereof, the hematocrit of the sample can be a source of analytical error in the ultimate analyte concentration measurement. Thus, in electrochemical measurement protocols where the analyte concentration is derived from observed time-current transients, increased hematocrit levels can increase the sample viscosity, which in turn, can slow the diffusion of enzyme, analyte, and mediator, thereby attenuating the test current and causing analytical error. Additionally, a partial fill or a double-fill of a sample-receiving chamber, a defective test strip, and/or leakage of sample can result in incorrect and/or inefficient testing.